Delete web taxonomy function

An attempt to delete a web taxonomy resulted in

Notice: Undefined index: vid in web_taxonomy_form_vocabulary_submit() (line 260 of /opt/labs/sites/all/modules/web_taxonomy/web_taxonomy.module).

PDOException: SQLSTATE[25P02]: In failed sql transaction: 7 ERROR: current transaction is aborted, commands ignored until end of transaction block: SELECT 1 AS expression FROM {web_taxonomy_vocabulary} web_taxonomy_vocabulary WHERE ( (vid IS NULL ) ) FOR UPDATE; Array ( ) in web_taxonomy_form_vocabulary_submit() (line 270 of /opt/labs/sites/all/modules/web_taxonomy/web_taxonomy.module).

Such a function would be nice for cleaning up (though priority is low).